How explicable are differences between reviews that appear to address a similar research question? A review of reviews of physical activity interventions

Background Systematic reviews are promoted as being important to inform decision-making. However, when presented with a set of reviews in a complex area, how easy is it to understand how and why they may differ from one another? Methods An analysis of eight reviews reporting evidence on effectiveness of community interventions to promote physical activity. We assessed review quality and investigated overlap of included studies, citation of relevant reviews, consistency in reporting, and reasons why specific studies may be excluded. Results There were 28 included studies. The majority (n = 22; 79%) were included only in one review. There was little cross-citation between reviews (n = 4/28 possible citations; 14%). Where studies appeared in multiple reviews, results were consistently reported except for complex studies with multiple publications. Review conclusions were similar. For most reviews (n = 6/8; 75%), we could explain why primary data were not included; this was usually due to the scope of the reviews. Most reviews tended to be narrow in focus, making it difficult to gain an understanding of the field as a whole. Conclusions In areas where evaluating impact is known to be difficult, review findings often relate to uncertainty of data and methodologies, rather than providing substantive findings for policy and practice. Systematic ?maps? of research can help identify where existing research is robust enough for multiple in-depth syntheses and also show where new reviews are needed. To ensure quality and fidelity, review authors should systematically search for all publications from complex studies. Other relevant reviews should be searched for and cited to facilitate knowledge-building

Gene Expression Microarray Results.

A) A diagram showing the process for identifying genes with altered expression: the false discovery rate (FDR) was calculated using BH method to limit the FDR to at most 2 expected false positive results in the all rejected null hypotheses (FDR = 16.6%). These results were further limited to genes with the largest fold changes (fold change > 20%). The identified genes are listed along with their fold changes relative to randomly oriented scaffolds. B) Pathway diagram illustrating where the protein products of several of the identified genes work to promote actin production and polymerization and focal adhesion assembly.</p

Electrospinning Apparatus and Resulting Nanofibers.

<p>A) Diagram of the electrospinning set-up: A polymer solution is extruded from a syringe into a high-voltage electric field towards a grounded cylindrical collector. When the collector is rotating at high RPM, aligned fibers are collected; when the collector is rotating at low RPM, randomly oriented fibers are collected. B) Example SEM images of nanofibers collected under various conditions. Scale bars are 10 microns.</p

Microscope images showing cells growing on random (top) or aligned (bottom) electrospun PCL+Gel fibers.

Fluorescent images are shown on the left with the cells stained to show the nuclei and stress fibers. The central column shows the distribution of cell orientations, confirming the cells on aligned fibers have a preferred orientation. Electron microscope images are shown on the right to illustrate the cellular interactions with the substrate. All image scale bars are 20μm.</p

Hydrophilicity Quantification.

A) A water drop on 100% PCL, the hydrophobic surface produces a large contact angle. B) A water drop on PCL+Gel surface, the gelatin increases the hydrophilicity of the surface producing a smaller contact angle. The data shows a clear change in contact angle induced by the addition of gelatin into the electrospun fiber mat.</p

Nanofiber Alignment Regulates NIH3T3 Cell Orientation and Cytoskeletal Gene Expression on Electrospun PCL+Gelatin Nanofibers

<div><p>To examine the influence of substrate topology on the behavior of fibroblasts, tissue engineering scaffolds were electrospun from polycaprolactone (PCL) and a blend of PCL and gelatin (PCL+Gel) to produce matrices with both random and aligned nanofibrous orientations. The addition of gelatin to the scaffold was shown to increase the hydrophilicity of the PCL matrix and to increase the proliferation of NIH3T3 cells compared to scaffolds of PCL alone. The orientation of nanofibers within the matrix did not have an effect on the proliferation of adherent cells, but cells on aligned substrates were shown to elongate and align parallel to the direction of substrate fiber alignment. A microarray of cyotoskeleton regulators was probed to examine differences in gene expression between cells grown on an aligned and randomly oriented substrates. It was found that transcriptional expression of eight genes was statistically different between the two conditions, with all of them being upregulated in the aligned condition. The proteins encoded by these genes are linked to production and polymerization of actin microfilaments, as well as focal adhesion assembly. Taken together, the data indicates NIH3T3 fibroblasts on aligned substrates align themselves parallel with their substrate and increase production of actin and focal adhesion related genes.</p></div

Proliferation assay of NIH 3T3 cells growing on various substrates.

<p>A) The average amount of DNA for cells grown on each substrate at 0 and 4 days. The DNA content is directly proportional to the number of cells. B) The cellular growth rate on various substrates as determined by the ratio of DNA content on days 0 and 4. This data indicates that orientation of the fibrous substrate does not influence the initial attachment or growth rate of NIH3T3 cells. However, the addition of gelatin does a substantially increase the growth rate over 100% PCL matrices (P<0.05, 2-way ANOVA, Tukey post-hoc). Error bars are ±SD.</p

Polymer Characterization.

<p>A) Fourier Transform Infrared Spectroscopy (FTIR) of samples of electrospun gelatin, PCL, and PCL+Gel blend. The data PCL+Gel shows a characteristic N-H stretch peak for amines at 3300 1/cm. This confirms the presence of gelatin within the electrospun matrix. B) Differential Scanning Calorimetry (DSC) of samples of electrospun gelatin, PCL, and PCL+Gel blend. The data indicates that the addition of gelatin to the PCL does not drastically change the crystallinity or melting point of the PCL.</p

Dynamic Phase Engineering of Bendable Transition Metal Dichalcogenide Monolayers

Current interest in two-dimensional (2D) materials is driven in part by the ability to dramatically alter their optoelectronic properties through strain and phase engineering. A combination of these approaches can be applied in quasi-2D transition metal dichalcogenide (TMD) monolayers to induce displacive structural transformations between semiconducting (H) and metallic/semimetallic (T′) phases. We classify such transformations in Group VI TMDs, and formulate a multiscale, first-principles-informed modeling framework to describe evolution of microstructural domain morphologies in elastically bendable 2D monolayers. We demonstrate that morphology and mechanical response can be controlled via application of strain either uniformly or through local probes to generate functionally patterned conductive T′ domains. Such systems form dynamically programmable electromechanical 2D materials, capable of rapid local switching between domains with qualitatively different transport properties. This enables dynamic “drawing” of localized conducting regions in an otherwise semiconducting TMD monolayer, opening several interesting device-relevant functionalities such as the ability to dynamically “rewire” a device in real time

Additional file 1: of Phage spanins: diversity, topological dynamics and gene convergence

Figure S1. Flowchart showing the manual search protocol to identify potential spanin candidates from genomes of phages infecting Gram-negative hosts. All the corrected CDS collected from the phage genome were run through TMHMM 2.0 and LipoP 1.0 with default parameters. Any CDS from the output with an N-terminal TMD or a C-terminal TMD or an N-terminal lipoylation signal sequence were further investigated as described. This manual search was supplemented by the automated FindSpanin workflow on the CPT Galaxy instance [32]. Once a spanin candidate was confirmed and curated, it was added to the online SpaninDB [33] and served as a query to find other potential candidates using BLAST. (PDF 77 kb